I started growing blueberry plants back in 2009, and they finally started producing last year, and I'm finally starting out to figure out how to get good production on these plants. Here's the old blog on them. http://stevespeonygarden.blogspot.com/2011/04/over-view-of-blueberries.html
Here's a view from the distance on how all the plants are doing. I mixed in a lot of peat moss & pine mulch into the bed to acidify the soil so the roots can reach into the soil.
The 1 gallon plants that were purchased on a clearance sale at $2 a piece from Lowes appear to plants from cuttings, and therefore don't have a clumping base that continually produces new canes from a crown. This means that all of the growth has to go through the existing stem which really limits the size, vigor and production of the plant, but there's a way to fix that.
Here's one of my 1 gallon plants in the ground.
Here's the base of this plant which shows that the crown is non-existant, and all of the energy is getting directed through 1 woody stem.
As I suspected, the roots never grew out outside of the 1 gallon confinement it was in which you can easily tell due to the pot shape of the root ball.
One solution that has worked for me last year on some of the blueberries that ended up losing their vigor due to this was to pot them up deeply into a larger pot filled with peat moss, pine mulch, and compost. This is exactly what I am doing with this one. The most important thing is to plant it nice and deep so that roots can form from the branches, and a crown that produces new canes can form.
The soil that comes in contact with the branches will cause them to generate new roots, especially with the clonex and willow tea that I plan on watering it with. The goal is to help them produce new canes, and bring the blueberry plant back to good health.
I added some milorganite, azomite, ironite, and watered it thoroughly to ensure that it takes off. The growth of new canes won't happen until after the blueberries are harvested since it takes the blueberry plant a lot of energy to produce them.
Here's a couple of the other ones that I did the same thing with.
Blueberries will end up being very small, and less tasteful if there are too many of them, and the plant is not vigorous enough.
Here's a closeup of the loss in vigor since a blueberry plant cannot thrive forever on the same woody stem. They need to produce new canes from their crown to continue growing vigorously. This one should recover by late summer. this plant almost died from trying to produce too many blueberries, but I took them all off in time, and it has since started to recover.
Here's one of the blueberry plants that I did this to last year however I only used 5 gallon pots which happened to be too small as it grew root-bound last year, and this is why I decided to use 15 gallon pots instead.
Notice how vigorous the new cane is that is coming out of the crown which formed last year.
Here's a closeup of the bottom of the new cane. Hopefully more canes will form this year.
A vigorous plant that has plenty of leaves and new growth will produce larger blueberries.
If you are growing a blueberry plant that is already healthy has a crown, and multiple canes, one way to help them spread is to ground layer the new canes which involves bending them down so that a section of that cane is under the soil to produce roots. This will cause a new crown to form at that site. Once new crowns are formed, or if rooting has already occured, I can sever it from the mother plant and transplant them somewhere else.
Everything in this picture is the same plant.
For this one, I only ground layered 2 canes at the bottom of the picture.
I can also use the ground layer technique on the 2 year old seedlings. The only major concern is to avoid over-watering the younger plants because it can cause them to drown and wilt away. In these pictures, I used a rock to help hold down one of the canes.
Here's my strongest 2 year old seedling.
Here are some examples of bad drainage. If it looks like one of the blueberry plants is going to die like this, one way to save it is to pot it up in a peat moss/ pine mulch/ compost mix that drains very well.
1 year old seedling